Light emitting diodes (LEDs) are being used more frequently in general illumination applications where they will have to provide high-intensity, constant user-specified color. In order to provide high-intensity light, packages containing multiple LED chips (of the same or different colors) must be used to avoid bulky lamps. We will refer to these below as “multi-chip LED packages”.
Light intensity and other properties vary among LED chips. This can cause color variations in light output from multi-chip LED packages. Light intensity and color of a multi-chip LED package can be measured and kept constant with the use of optical sensors and supporting electronics and control systems which are positioned in packages separate from the LED chips. To obtain LED lamps that are compact, consistent in light output, and that require minimal design work from the lamp designer using multi-chip LED packages, integration of the sensors (and possibly other electronics) in the LED package is desirable. Placement of the sensors so that they provide useful signals for control of light output, then would be critical.
It would be desirable, therefore, to provide a system and method for maintaining light characteristics of multi-chip LED packages that overcomes these and other disadvantages.